EP1600422A1 - Process for the preparation of molecular hydrogen and polyaluminium chloride - Google Patents

Abstract

Preparation of molecular hydrogen (I) comprises adding metallic aluminum and/or aluminum alloy in an aqueous aluminum chloride solution and dissolving under the formation of polyaluminumchloride. Independent claims are also included for: (1) a method of operating a fuel cell (with an anode and a cathode) comprising preparing (I) by the preparative method, which is led directly (through a hydrogen permeable membrane (16)) to the anode (14) of the fuel cell (13); and (2) a device, for producing electricity, comprising fuel cell (consisting an anode and a cathode (15)), a chamber (2) (for receiving the metallic aluminum and/or aluminum alloy), a solvent container (3) (for receiving the aqueous aluminum chloride solution), where the solvent container and the chamber are connected by a rheostat and the chamber and the fuel cell are connected by a hydrogen permeable membrane, where during the operation of the device, the molecular hydrogen is led through the chamber via the permeable membrane to the anode of the fuel cell.

Description

The present invention relates to a process for the production of molecular Hydrogen with simultaneous formation of polyaluminum chloride, a Method for operating a fuel cell and a device for the Generating electrical energy comprising a fuel cell.

Molecular hydrogen is used in a variety of chemical processes, For example, as a starting material, reducing agent, hydrogenating agent or the like., Or as Fuel, for example. In fuel cells used. Known method for the production of molecular hydrogen can be divided into two groups, namely, on the one hand the chemical conversion of primary hydrogen-containing Energy sources, such as methane, coal, refinery products and the like., In reforming process and second, the electrolytic production of hydrogen of water. However, all of the aforementioned methods are, in particular as far as the production of high purity hydrogen is concerned, consuming and costly. While doing so in the methods according to the former Group and others due to the fact that the hydrogen formed by the inevitably contaminated in the reforming by-products and this is therefore purified in several downstream process steps must be, this lies in the electrolysis process in the high operating costs for the electrolysis and the high investment costs of the electrolysis devices founded.

Object of the present invention is therefore to provide an alternative method for Production of molecular hydrogen to provide, in particular the cost-effective production of high purity hydrogen allows.

According to the invention this object is achieved by a method according to claim 1 solved.

In the context of the present invention it could be found that molecular hydrogen with a satisfactory yield and high purity by dissolving metallic aluminum and / or an aluminum alloy in an aqueous aluminum chloride solution, the yield to hydrogen, based on the amount of aluminum used of the process parameters is 80 to 98%. Due to the high purity The generated molecular hydrogen can be a subsequent costly Purification as known in the art Reforming process is mandatory, be waived. Only when carrying out the process according to the invention at elevated temperatures the generated hydrogen is contaminated with traces of water vapor, However, in a simple manner, for example. In a condensation chamber, of the molecular hydrogen can be separated. The generated hydrogen can subsequently be used for energy generation, for example in combination with fuel cells, be used. In addition, in the method according to the invention receive a polyaluminum chloride solution in addition to molecular hydrogen, which is sufficiently pure to be used in papermaking or water preparation to be used. So far, polyaluminium chloride has been either by pressure digestion of aluminum hydroxide by means of hydrochloric acid in one Autoclave or by anodic dissolution of metallic aluminum produced in electrolysis cells. Both methods, however, are due to the the pressure digestion or the electrolysis conditional high operating costs costly. Apart from a cost-effective production of high-purity molecular hydrogen allows the process of the invention hence also one compared to those known in the art Process more cost-effective production of polyaluminum chloride. Another Advantage of the method lies in its flexibility, which The reason for this is that the amount of hydrogen produced depends solely on the amount and the reactivity of the aluminum used depends. That's it possible, the amount of hydrogen to be generated as needed in the range of a few milliliters per hour up to several thousand cubic meters per hour adjust.

In principle, all types can be used in the method according to the invention Aluminum alloys and / or aluminum in all degrees of purity, eg in Shavings, films or the like., Can be used. Especially good results however, are obtained when metallic aluminum with a degree of purity from 98 to 99.99% and / or an aluminum alloy at 0.01 to 1 g / kg Aluminum in metals selected from among copper, iron, silicon, manganese, Magnesium, nickel, zinc and combinations thereof is used.

According to a particular embodiment of the present invention, the metallic aluminum and / or the aluminum alloy prior to insertion into the aqueous aluminum chloride solution a chemical and / or electrochemical Subjected to etching process to roughen its surface. Especially Preferably, the surface of the in the aqueous aluminum chloride solution introduced aluminum or aluminum alloy tunnel structures with a diameter of less than 2 microns, and most preferred less than 100 nm. Alternatively, it is, albeit less preferred, possible, aluminum or an aluminum alloy with a smooth or slightly roughened Surface to use.

In order to remove any trapped air in the starting material is Preferably, the metallic aluminum and / or the aluminum alloy the introduction into the aqueous aluminum chloride solution with an inert gas atmosphere, For example, nitrogen, argon or the like., Rinsed.

In the context of the present invention, it has been found that particularly good Results are obtained in terms of yield, if used aqueous aluminum chloride solution has a content of aluminum chloride of 1 to 400 g / l, more preferably 20 to 130 g / l and most preferably from 20 to 50 g / l.

In a further development of the inventive concept, it is proposed that the aqueous Aluminum chloride solution one or more corrosion inhibitors, especially preferably at least one organic corrosion inhibitor selected from consisting of carboxylic acids, amines, alcohols and derivatives thereof Group and / or selected at least one inorganic corrosion inhibitor from that consisting of sulfuric acid, nitric acid and phosphoric acid Group, add.

Particularly good results are achieved when the aqueous aluminum chloride solution in addition to one or more corrosion inhibitors also one or a plurality of corrosion activators, more preferably at least one metal chloride and most preferably at least one chloride of a metal is selected from the group consisting of iron, copper, nickel and zinc. However, it is possible, albeit less preferred, for the aluminum chloride solution only add corrosion activators.

To a high yield of molecular hydrogen, based on the amount to get used aluminum, is in development of the inventive concept proposed, the aqueous aluminum chloride solution during the Dissolution of the metallic aluminum and / or aluminum alloy a temperature of 10 to 100 ° C, more preferably 50 to 100 ° C and most preferably from 95 to 100 ° C, adjust.

In order to avoid unwanted oxidation reactions, the resolution of metallic aluminum and / or aluminum alloy in the aqueous Aluminum chloride solution preferably under inert gas atmosphere and especially preferably carried out under a nitrogen atmosphere.

In a further development of the inventive concept, it is proposed to have a ratio of aluminum (in the form of metallic aluminum and / or an aluminum alloy) to aqueous aluminum chloride solution of from 100 to 5,000 m ² , more preferably from 250 to 2,000 m ² and most preferably about 500 m ² Adjust aluminum per m ^{3 of} solvent.

In particular when carrying out the process according to the invention in the industrial Scale, it has a continuous process management advantageous proved. This can be done, for example, in such a way that the aqueous aluminum chloride solution in the circuit by a pack of aluminum and / or an aluminum alloy and the gaseous reaction products by introducing molecular nitrogen with an overpressure from the reaction chamber removed and polyaluminium chloride continuously or discontinuously is withdrawn from the reaction mixture.

The hydrogen produced according to the invention can be known to all those skilled in the art Purposes are used, especially for energy or as a raw material for chemical reactions.

Another object of the present invention is methods of operation a fuel cell comprising an anode and a cathode. According to the invention is provided that with the invention described above Process produced molecular hydrogen through a hydrogen permeable Membrane as fuel directly to the anode of a fuel cell where it oxidizes to hydrogen ions and on entering in the electrolytes with doubly negatively charged ones formed at the cathode Oxygen ions is converted to water. Preferably, the at Operation of the fuel cell formed water to the aqueous aluminum chloride solution recycled.

For the process according to the invention, all known to those skilled in the art Fuel cells are used, which consist of hydrogen and oxygen forming water while generating electrical energy. Usually wise Such fuel cells have a 50 to 70% energy yield and are operated with a voltage of about 0.7 volts. Individual fuel cells are conventionally stacked, so-called. Stacks summarized, wherein the performance of the device is proportional to the number of fuel cells is.

Moreover, the present invention relates to a device for generating electrical energy, which in particular for the mobile operation of a fuel cell suitable is. According to the invention, the device comprises at least an anode and a cathode having fuel cell, a chamber for receiving metallic aluminum and / or an aluminum alloy and a solvent container for holding an aqueous aluminum chloride solution, wherein the chamber and the solvent container via a lockable conduit are connected together, and, being the chamber and the fuel cell via a hydrogen permeable membrane such connected during operation of the device molecular hydrogen of the chamber is passed through the membrane to the anode of the fuel cell.

The invention will be described below with reference to embodiments and the Drawing explained in more detail. All are described and / or illustrated features illustrated the subject of the invention, regardless of their Summary in the claims or their dependency.

Fig. 1

ein Prozessdiagramm eines Verfahrens und einer Vorrichtung zur Herstellung von Wasserstoff gemäß eines Ausführungsbeispiels der vorliegenden Erfindung, und

Fig. 2

ein Prozessdiagramm eines Verfahrens und einer Vorrichtung zum Erzeugen elektrischer Energie für einen mobilen Einsatz einer Brennstoffzelle gemäß eines Ausführungsbeispiels der vorliegenden Erfindung.

Show it:

Fig. 1

a process diagram of a method and an apparatus for producing hydrogen according to an embodiment of the present invention, and

Fig. 2

a process diagram of a method and apparatus for generating electrical energy for mobile use of a fuel cell according to an embodiment of the present invention.

The device shown in FIG. 1 comprises a cylindrical reactor 1 made of steel with a useful volume of about 10 m ³ , which is divided into a chamber 2 for receiving aluminum and / or an aluminum alloy and a solvent chamber 3. In order to enable a process to be carried out at elevated temperatures, for example at 100 ° C., without addition of corrosion activators with external heating, the reactor is preferably designed as double-walled, with the reactor inner wall particularly preferably made of heat-resistant and corrosion-resistant material, such as ceramic, Teflon , Polypropylene or the like. The reactor is preceded by a pre-chamber 4, which has both a solid supply line 5 and a gas supply line 6 for inert gas and is connected to the reactor. In addition, the reactor 1 has a liquid supply line 7, a liquid circulation line 8 and two product discharge lines 9, 10 for generated hydrogen and polyaluminium chloride, wherein the hydrogen discharge line 9 leads to a condensation chamber 11, a gasometer 12 and an energy converter 13 are connected downstream.

For the operation of the apparatus described above, aluminum and / or an aluminum alloy in the form of chips or foils is first passed via the line 5 into the prechamber 4, where it is purged with excess pressure via line 6 supplied inert gas, preferably nitrogen, to any trapped in the starting material Remove air before the aluminum and / or the aluminum alloy is conveyed into the reactor chamber 2 on. Fresh aqueous aluminum chloride solution is constantly supplied to the reactor 1 via the liquid supply line 7 and mixed with aqueous aluminum chloride solution already passed through the reactor chamber 2 in the solvent chamber 3, after which this mixture is again supplied via the liquid circulation line 8 to the reactor chamber 2 containing aluminum. The feed rates of aluminum or aluminum alloy and of fresh aqueous aluminum chloride solution and the stream of aluminum chloride solution passed through the circulation line 8 are adjusted such that a constant ratio of approximately 500 m ^{2 of} aluminum per m ^{3 of} solvent is established in the reactor chamber 2. Formed polyaluminum chloride, which is detected by pH and density measurements, is withdrawn via the product discharge line 10, whereas the generated molecular hydrogen containing traces of water vapor is supplied by the nitrogen flow via the line 9 of the condensation chamber 11, in which water vapor from the hydrogen is separated. This separation is controlled by a moisture meter depending on the desired moisture content of the generated hydrogen gas. The hydrogen is then intermediately stored with the aid of a gasometer in order to adapt to the consumption of the downstream energy converter 13, for example a fuel cell or gas turbine.

In the reactor described above about 500 m ^{3 of} hydrogen per hour can be generated and converted with the current efficiency data with a capacity of 500 kW in electrical energy.

The device shown in Fig. 2 comprises in addition to a chamber for aluminum or aluminum alloy 2 and a solvent chamber 3 a conventional fuel cell 13, which has an anode 14 and a cathode 15 includes. The fuel cell 13 is separated from the chamber 2 by a hydrogen permeable one Membrane 16 so separated that during operation of the device molecular hydrogen from the chamber 2 through the membrane 16 to the anode 14 of the fuel cell 13 is guided. To the hydrogen evolution to to record or finish the desired time is between the Solvent chamber 3 and the chamber 2 for aluminum or aluminum alloy a closure mechanism 17 is provided, via which the supply of aqueous Aluminum chloride solution from the solvent chamber 3 to the chamber 2 can be adjusted. In the fuel cell 13 formed water is over a line 18 is guided in the solvent chamber 3.

With the device described above, for example, at a reactor volume of 50 ml and 10 g of aluminum about 20 Wh of energy are generated when the fuel cell 13 has a 60% efficiency.

LIST OF REFERENCE NUMBERS

1

reactor

2

(Reactor) chamber for aluminum

3

Solvent chamber

4

antechamber

5

Solid feed line for aluminum

6

Gas supply line for inert gas

7

Liquid supply line

8th

Liquid circulation line

9

Product discharge line for hydrogen

10

Product discharge line for polyaluminum chloride

11

condensation chamber

12

gasometer

13

Power converter / fuel cell

14

anode

15

cathode

16

membrane

17

locking mechanism

18

Water return line

Claims (16)

Process for the preparation of molecular hydrogen, characterized in that metallic aluminum and / or an aluminum alloy is introduced into an aqueous aluminum chloride solution and dissolved to form polyaluminum chloride. A method according to claim 1, characterized in that metallic aluminum is used with a purity of 98 to 99.99%. A method according to claim 1 or 2, characterized in that an aluminum alloy with 0.01 to 1 g / kg of aluminum is used on metals selected from the group consisting of copper, iron, silicon, manganese, magnesium, nickel, zinc and combinations thereof. Method according to one of the preceding claims, characterized in that the metallic aluminum and / or the aluminum alloy is subjected to a chemical and / or electrochemical etching process prior to introduction into the aqueous aluminum chloride solution. A method according to claim 4, characterized in that the surface of the introduced into the aluminum chloride aqueous solution aluminum and / or the aluminum alloy tunnel structures having a diameter of less than 2 microns and preferably less than 100 nm. Method according to one of the preceding claims, characterized in that the metallic aluminum and / or the aluminum alloy is rinsed before being introduced into the aqueous aluminum chloride solution with an inert gas atmosphere for the removal of trapped air in the starting material. Method according to one of the preceding claims, characterized in that an aqueous aluminum chloride solution with a content of aluminum chloride of 1 to 400 g / l, more preferably 20 to 130 g / l and most preferably from 20 to 50 g / l is used. Method according to one of the preceding claims, characterized in that the aqueous aluminum chloride solution, one or more corrosion inhibitors, more preferably at least one organic corrosion inhibitor selected from the group consisting of carboxylic acids, amines, alcohols and derivatives thereof and / or at least one inorganic corrosion inhibitor selected from Sulfuric acid, nitric acid and phosphoric acid group containing. Method according to one of the preceding claims, characterized in that the aqueous aluminum chloride solution contains one or more corrosion activators, more preferably at least one metal chloride, and most preferably at least one chloride of a metal selected from the group consisting of iron, copper, nickel and zinc. Method according to one of the preceding claims, characterized in that the aqueous aluminum chloride solution during the dissolution of the metallic aluminum and / or the aluminum alloy, a temperature of 10 to 100 ° C, more preferably from 50 to 100 ° C and most preferably from 95 to 100 ° C, has. Method according to one of the preceding claims, characterized in that the dissolution of the metallic aluminum and / or the aluminum alloy in the aqueous aluminum chloride solution is carried out under an inert gas atmosphere and particularly preferably under a nitrogen atmosphere. Method according to one of the preceding claims, characterized in that a ratio of aluminum as a solid to aqueous aluminum chloride solution of 100 to 5,000 m ² , more preferably from 250 to 2,000 m ² and most preferably adjusted by about 500 m ^{2 of} aluminum per m ^{3 of} solvent becomes. Method according to one of the preceding claims, characterized in that it is carried out continuously by circulating the aqueous aluminum chloride solution through a packing of aluminum and / or an aluminum alloy, removing gaseous reaction products by introducing molecular nitrogen with an overpressure from the reaction chamber and polyaluminum chloride withdrawn continuously or discontinuously from the reaction mixture. A method of operating a fuel cell having an anode and a cathode, characterized in that molecular hydrogen according to one of claims 1 to 13 prepared and this is passed through a hydrogen-permeable membrane (16) directly to the anode (14) of a fuel cell (13). A method according to claim 14, characterized in that the water formed during operation of the fuel cell (13) is fed to the aqueous aluminum chloride solution. Device for generating electrical energy comprising at least a fuel cell having an anode (14) and a cathode (15) (13), a chamber (2) for receiving metallic aluminum and / or an aluminum alloy and a solvent container (3) for receiving an aqueous aluminum chloride solution, wherein the chamber (2) and the solvent container (3) connected to each other via a closable line are, and, wherein the chamber (2) and the fuel cell (13) via a hydrogen-permeable Membrane (16) are connected such that during operation of the Device molecular hydrogen from the chamber (2) through the membrane (16) to the anode (14) of the fuel cell (13) is guided.

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